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dlasq3.f(3) | LAPACK | dlasq3.f(3) |
NAME¶
dlasq3.f -SYNOPSIS¶
Functions/Subroutines¶
subroutine dlasq3 (I0, N0, Z, PP, DMIN, SIGMA, DESIG, QMAX, NFAIL, ITER, NDIV, IEEE, TTYPE, DMIN1, DMIN2, DN, DN1, DN2, G, TAU)
Function/Subroutine Documentation¶
subroutine dlasq3 (integerI0, integerN0, double precision, dimension( * )Z, integerPP, double precisionDMIN, double precisionSIGMA, double precisionDESIG, double precisionQMAX, integerNFAIL, integerITER, integerNDIV, logicalIEEE, integerTTYPE, double precisionDMIN1, double precisionDMIN2, double precisionDN, double precisionDN1, double precisionDN2, double precisionG, double precisionTAU)¶
DLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr. Purpose:DLASQ3 checks for deflation, computes a shift (TAU) and calls dqds. In case of failure it changes shifts, and tries again until output is positive.
I0
Author:
I0 is INTEGER First index.N0
N0 is INTEGER Last index.Z
Z is DOUBLE PRECISION array, dimension ( 4*N ) Z holds the qd array.PP
PP is INTEGER PP=0 for ping, PP=1 for pong. PP=2 indicates that flipping was applied to the Z array and that the initial tests for deflation should not be performed.DMIN
DMIN is DOUBLE PRECISION Minimum value of d.SIGMA
SIGMA is DOUBLE PRECISION Sum of shifts used in current segment.DESIG
DESIG is DOUBLE PRECISION Lower order part of SIGMAQMAX
QMAX is DOUBLE PRECISION Maximum value of q.NFAIL
NFAIL is INTEGER Number of times shift was too big.ITER
ITER is INTEGER Number of iterations.NDIV
NDIV is INTEGER Number of divisions.IEEE
IEEE is LOGICAL Flag for IEEE or non IEEE arithmetic (passed to DLASQ5).TTYPE
TTYPE is INTEGER Shift type.DMIN1
DMIN1 is DOUBLE PRECISIONDMIN2
DMIN2 is DOUBLE PRECISIONDN
DN is DOUBLE PRECISIONDN1
DN1 is DOUBLE PRECISIONDN2
DN2 is DOUBLE PRECISIONG
G is DOUBLE PRECISIONTAU
TAU is DOUBLE PRECISION These are passed as arguments in order to save their values between calls to DLASQ3.
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 181 of file dlasq3.f.
Author¶
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